The present invention concerns a novel process and system for treating fluid. Although the illustrative embodiments of the invention primarily concern the recharging of a resin bed in a water softener, the present invention is also applicable to fluid treatment including the backwashing of a filter in a water purification system, the removal of selected constituents from water, the adjustment of the concentration of brine in a water softener system, and other fluid treatments which will become apparent from the description.
There are presently several methods of determining when recharging of the resin bed in a water softener is required. In one method, the electrical resistance of the resin bed is determined. The resistance of the resin bed forms one arm of a resistive bridge, and once a selected resistance is determined, recharging is required. Another system for determining whether recharging is required is by using a flow meter. The flow meter is used to determine the amount of water that has been used. Once a selected volume of water has been used as indicated by the flow meter, the system is recharged. However, a flow meter is relatively expensive and needs certain supporting hardware. In addition, certain flow meters are subject to failure as a result of iron and/or turbidity fouling the impellers of the flow meter. The turbine blade is generally formed of plastic material with numerous vanes, and the iron in the water may plate the vanes, eventually forming an obstruction to proper rotation of the turbine.
Another method of determining when recharging should occur is simply to recharge the resin bed every few days. This method can be very wasteful, however, and on the other hand can be too infrequent for various households.
In addition to determining when recharging should occur, when water softeners are concerned one must consider the condition of the brine tank. It is preferable for the brine tank to contain the proper amount of saturated brine solution at the time of recharging. The recharging comprises bathing the resin in brine to remove hardness impurities and then rinsing the resin free of excess brine. Thus, during service the raw water flows into the softener tank, through the tank and out of the tank through a flow switch to the household. The brine tank, which is coupled to the system, is isolated during service. During recharging, the softener tank is backwashed by directing the inlet water to the bottom of the tank through a manifold and then backwashing the ion exchange resin with the water flowing upwardly and out of the softener tank to drain. Brine is then directed from the brine tank to the softener tank, to the manifold and through the softener tank and then to drain. The rinsing step comprises directing the inlet water into the softener tank in the usual manner and washing out the brine to rinse out the tank, although instead of directing the flow from the outlet line to the household, the rinse water flows to drain.
It can be seen that when a water softener is recharged, brine is drawn up from the brine tank into the resin bed of the water softener. After the recharging process is completed, more brine has to be made. It is important that a sufficient saturated brine solution be available at the next recharging time.
I have discovered a novel process and system for recharging the resin in a water softener and my process and system are also useful for other water treatments. In utilizing my invention, there is no need to determine the electrical resistance of the resin bed, nor is the use of a flow meter required in most embodiments of my invention. Further, the problems concomitant with simply recharging a resin bed every few days are alleviated by my process and system. By using my novel fluid treatment process and system, the fluid may be treated when required, at a selected time of day if desired, at a selected day or days of the week, as desired, and in a water softener system a proper volume of saturated brine solution will be available at the time of recharging the resin bed.